Adjustable electromagnetic coupling apparatus



June 6, 1967 R. H. SWARTLEY 3,324,425

ADJUSTABLE ELECTROMAGNETIC COUPLING APPARATUS Filed June 24, 1965 1. 9. S INVENTOR.

RICHARD H. SWARTLEY ATTORNEY United States Patent 3,324,425 ADJUSTABLE ELECTRGMAGNETIC COUPLING AFPARATUS Richard H. Swartley, San Carlos, Calif., assignor, by

mesne assignments, to Varian Associates, a corporation of California Filed June 24, 1965. Ser. No. 466,656 9 Claims. (Cl. 333--24) This invention relates to the coupling of electromagnetic energy and more specifically to coaxial apparatus for varying the coupling of electromagnetic energy into or out of structures capable of containing this energy, such as resonant cavities, waveguides and the like.

An object of this invention is to provide improved electromagnetic coupling apparatus that is easily adjusted.

Still another object of this invention is to provide improved electromagnetic coupling apparatus that is adaptable to either capacitive or inductive probes and which can easily be tuned without breaking the RF path within an electromagnetic energy containing structure.

A further object of this invention is to provide a means for locking an electromagnetic energy coupling apparatus once an optimum, or otherwise desired, coupling is achieved with no altering of the selected condition.

These and other objects are accomplished, in accordance with the present invention, by an electromagnetic coupling apparatus which comprises a hollow structure capable of containing electromagnetic energy therein and having an aperture in a sidewall thereof, a partially threaded tubular insert with slots cut in each end fixed in said sidewall aperture, a locking nut working in conjunction with said partially threaded section of said tubular insert, and a coaxial line terminating with either a capacitive or inductive probe. The coaxial line extends through the locking nut and the tubular insert and may be either slid axially or rotated freely therein. The locking nut, with a combination internal threaded and tapered section matching a similar combination external threaded and tapered section on the tubular insert, is tightened on said tubular insert so that the combined mechanisms action is to circumferentially clamp the coaxial conductor Within the tapered, slotted end of the tubular insert when the desired final coupling is accomplished. The slotted end at the non-locking end of the tubular insert is utilized in maintaining a continuous RF energy circuit within the cavity, even when coaxial conductor adjustments are being made, by maintaining constant contact with the metal outer conductor of the coaxial conductor.

This invention as well as other objects, features, and advantages thereof, will readily be apparent from consideration of the following detailed description relating to the annexed drawings in which:

FIGURE 1 illustrates, in partial cross-section, the electromagnetic energy coupling apparatus in accordance with the present invention;

FIGURE 2 is an exploded view, in perspective, of a coupling probe assembly, removed from the electromagnetic energy containing structure, according to this invention; and

FIGURE 3 illustrates, in partial cross-section, a coaxial line with a braided metal outer conductor and an inductive probe for use in the electromagnetic energy coupling apparatus shown in FIGURE 1.

Referring now to the drawings, wherein like reference characters represent like or corresponding parts throughout the several views, there is illustrated in FIGURE 1 an electromagnetic energy coupling apparatus fabricated in accordance with the present invention and which includes a hollow structure capable of containing electromagnetic energy within the hollow interior 12 thereof.

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The structure 10 may be a resonant cavity, waveguide or the like and preferably is designed for use in the microwave region of the electromagnetic spectrum. The structure 10 is fabricated from any suitable electrically con-l ductive material or any suitable electrically non-conductive material having an electrically conductive coating on the hollow interior 12 thereof.

Electromagnetic energy is first coupled to the hollow interior 12 of structure 10 from an RF energy exciting means which in the preferred embodiment shown is an RF modulated electron beam traveling axially in the general evacuated region 14. This coupling means is well understood by those familiar with the art of RF energy transfer. The hollow interior 12 is not necessarily vacuumsealed.

The subject of this invention is the electromagnetic energy coupling assembly comprised of the electromagnetic energy containing structure 10, coaxial electromagnetic energy coupler 2i (FIGURES 1, 2, and 3) and the coupler locking assembly 30. The coupler locking assembly 30 is itself comprised of a tubular insert 35 and a locking nut 45.

The electromagnetic energy is preferably coupled by either inserting a capacitive probe 21 terminated coaxial electromagnetic energy coupler 20 in the proximity of the RF modulated electron beam enclosure 15 or by inserting an inductive probe 22 terminated (FIGURE 3) coaxial electromagnetic energy coupler 20 in the proximity of the inner or maximum current carrying side of the outer wall 11 of the electromagnetic energy containing structure 10.

The coaxial electromagnetic energy coupler 23 is comprised of either a solid metal outer conductor 23 or a braided metal outer conductor 24, an inner metal conductor 25, a dielectric separator 26 maintaining a coaxial relationship between said outer and inner conductors, an optional protective or insulating cover 27 enclosing part of said metal outer conductor remote from the coupling locking assembly 30 when engaged, and either a capacitive probe 21 or an inductive probe 22 termination. The capacitive probe 21 termination will also include a dielectric washer insulator 28.

The coaxial electromagnetic energy coupler 20 is preferably terminated for further addition of the desired probe 21 or 22 by radially cutting through the outer metal conductor 23 or 24 and the dielectric separator 26 in a common plane perpendicular to the common axis thereof. The inner metal conductor 25 is not out along the aforementioned plane. The remaining section of inner metal conductor 25, or pigtail, lying between the aforementioned plane and the end of the coaxial line is cleaned and further prepared for the manufacture of the desired probe 21 or 22.

The capacitive probe 21 termination of the coaxial electromagnetic engaging coupler 20 is manufactured by sliding, Or otherwise including, a centrally punched dielectric washer insulator 28 over the prepared metal inner conductor 25 until it fits tightly against the surface of the aforementioned common cutting plane of the metal outer conductor 23 or 24 and the dielectric separator 26. The dielectric washer insulator 28 will preferably have an outer radius larger than the outer radius of the metal outer conductor 23 or 24 of the coaxial electromagnetic energy coupler 20. The dielectric washer insulator 28 will preferably also have a lip 29 which is a continuous homogeneous extension of the aforementioned dielectric washer insulator 28 extending axially away from the capacitive terminator 21 when added, and continuing a short way past, and enclosing, the terminal end of the metal outer conductor 23 or 2 The capacitive probe 21 is next added to hold the dielectric washer insulator 23 sandwiched snugly between itself and the common plane end of the cut metal outer conductor 23 or 24 and the dielectric separator 26. The capacitive probe 21 is now secured by soldering, brazing, etc. to the terminal end of the metal inner conductor 25 and a fiat, contoured or any other desired surface is ground or otherwise machined onto the terminal end of said capacitive probe 21.

The inductive probe 22 termination of the coaxial electromagnetic energy coupler is manufactured by preparing said coupler 20 similarly to preparing for the capacitive probe 21 termination except that no dielectric washer insulator 28 or capacitive probe 21 is added to the prepared said coupler 20. An inductive probe 22 is prepared by merely bending the free end of the metal inner conductor into a loop of any desired dimensions and welding, brazing, or otherwise attaching the terminal end of said metal inner conductor 25 to the terminal end of the metal outer conductor 23 or 24 as indicated at 31. The inductive probe 22 does not necessarily have to be in direct physical contact with the metal outer conductor 23 or 24 as shown at 31. A capacitive element, not shown, may be included therebetween.

The tubular insert is made with an external tapered section 36, an external threaded section 37, a mounting section 38 and a slotted terminal end 39. Slots are cut in the external tapered 36 end of the tubular insert 35 which continue on through the external threaded section 37 as far as the mounting section 38. The mounting section 38, shown threaded, may be tapered, cylindrical or of any other shape for engaging a matching aperture in the outer wall 11 of the electromagnetic energy containing structure 10. The individual slotted terminal end cantilevers 39 are dimensioned to specifically engage the metal outer conductor 23 or 24 of the coaxial electromagnetic energy coupler 20 during manufacture of said energy coupling assembly. The tubular insert 35 is preferably made from a good surface conducting material with good spring characteristics such as beryllium copper.

The locking nut is made with an internal thread 46 running part way through said locking nut 45 and an internal taper 47 continuing from the internal thread 46 almost to the other end of said locking nut 45. The internal thread 46 of the locking nut 45 matches the external thread 37 of the tubular insert 35 and the internal taper 47 of the locking nut 45 matches the external tapered section 36 of said tubular insert 35. The locking nut 45 may be made of any strong material; not necessarily metal.

The electromagnetic energy coupling probe assembly is manufactured by first preparing the terminal end of the coaxial electromagnetic energy coupler 20 for either a capacitive probe 21 or an inductive probe 22 as previously described, sliding the locking nut 45 onto said partially prepared said coupler 20 with the internal threaded section 46 nearest said terminal end, next sliding the tubular insert 35 onto said coupler 20 with the external tapered section 36 in conjunction with the locking nut 45, and then finishing the manufacture of either the capacitive probe 21 or the inductive probe 22. The mounting section 38 of the tubular insert 35 is then engaged into the matching aperture in the wall of the electromagnetic energy containing structure 10 and secured by staking, welding, RF brazing or any other retaining means by which the components of the coaxial electromagnetic energy coupler 20 are not physically or electrically altered. The locking nut 45 is next threadably engaged with the tubular insert 35 and tightened until the tapered sections 36 and 47 are in contact.

The electromagnetic energy containing structure 10 is excited and fine tuning with the coaxial electromagnetic energy coupler 20 may now be accomplished by sliding said coupler 20 axially for capacitive probe 21 terminated units or by rotating said coupler for inductive probe 22 terminated units. Once the desired tuning is accomplished, the coaxial electromagnetic energy coupler 20 may be secured by further tightening of the locking nut 45 which causes the external tapered section 36 of the tubular insert 35 to circumferentially grip the metal outer conductor 23 or 24. Circumferential gripping of the metal outer conductor 23 or 24 is preferable to localized locking, such as would occur with a single set screw, in that the gripped surface is not physically distorted as it would be with said localized locking means. This distortion could affect a finely tuned circuit by changing the coaxial line capacitance. Localized distortion, too, can make finer linear and rotational adjustments of the coaxial electromagnetic energy coupler difficult in that the set screw, or similar apparatus, will seek the center of a conical indentation formed by previous locking.

Another feature of this invention in addition to the circumferential gripping and ease of fine adjustment, is the slotted terminal end 39 of the tubular insert 35. When dimensioned properly, the individual cantilever tabs formed by the slot manufacturing process will fit tightly around the metal outer conductor 23 or 24 of the coaxial electromagnetic energy coupler 20 and affect an RF energy path directly from said metal outer conductor 23 or 24 of said coaxial coupler 20 to the inner side of the ,outer wall 11 of the electromagnetic energy containing structure 10. This RF energy path is maintained even when the locking nut 45 is loosened for fine adjustment.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than specifically described.

I claim:

1. An adjustable coupling apparatus for use with an electromagnetic energy containing structure having an aperture wall, said wall housing in spaced relation an inner electrical conductor, said apparatus com-prising:

(a) a tubular insert,

(b) a locking nut and (c) a coaxial line extending through said locking nut and said tubular insert and terminating in an electromagnetic energy probe located adjacent said inner electrical conductor and in spaced relation with said wall and said inner conductor,

(1) said tubular insert being dimensioned to freely receive said coaxial line and having an end portion provided with axially extending slots through the wall thereof and a solid central mounting portion, said end portion having an external threaded section and an external tapered section,

(2) said locking nut having an internal threaded section and an internal tapered section and being dimensioned to freely slide over said coaxial line, said internal threaded portion of said nut engaging said external threaded section of said insert and said internal tapered section of said nut engaging said external tapered section of said insert whereby when said nut is tightened onto said insert by engagement of said threaded sections, said slotted end portion of said insert is circumferentially clamped against said coaxial line by engagement of said tapered sections.

2. The combination defined in claim 1 wherein said electromagnetic energy coupler is a capacitive probe.

3. The combination defined in claim 1 wherein said electromagnetic energy coupler is an inductive probe.

4. The combination defined in claim 1 wherein said coaxial line has a solid metal outer conductor.

5. The combination defined in claim 1 wherein said coaxial line has a braided metal outer conductor.

6. An electromagnetic energy coupling probe for use with a resonant cavity comprising:

(a) a tubular insert,

(b) a locking nut and (c) a coaxial line with solid outer conductor extending through said locking nut and said tubular insert and terminating in a capacitive electromagnetic energy probe,

(1) said tubular insert being dimensioned to freely receive said coaxial line and having end portions provided with axially extending slots through the walls thereof and a solid external receive said coaxial line and having end portions provided with axially extending slots through the walls thereof and a solid central mounting portion separating said end portions, one of said slotted end portions having multiple parallel cantilevers contacting said coaxial line.

threaded central mounting portion separating said end portions, one of said slotted end portions having an external threaded section and an external tapered section, said other slotted 1 end portion having multiple parallel cantilevers contacting said coaxial line,

(2) said locking nut having an internal threaded section and an internal tapered section and being dimensioned to freely slide over said coaxial line, said internal threaded portion of said nut engaging said end portion external threaded section of said insert and said internal tapered section of said nut engaging said external tapered section of said insert whereby when said nut is tightened onto said insert by engagement of said internal threaded section of said nut and said external threaded end portion of said insert, said one sloted end portion of said insert is circumferentially clamped against said coaxial line by engagement of said tapered sections.

7. An adjustable coupling apparatus for use with an electromagnetic energy containing structure having an apertured wall and adjustable coupling apparatus, said wall housing in spaced relation an inner electrical conductor, said adjustable coupling apparatus comprising:

(a) a tubular insert and (b) a coaxial line extending through said tubular insert and terminating in an electromagnetic probe located adjacent said inner electrical conductor and in spaced relation with said wall and said inner conductor,

(1) said tubular insert being dimensioned to freely receive said coaxial line and having an end 9. A coupling apparatus for use with an electromagnetic energy containing structure having an apertured wall comprising:

(a) atubular insert,

(b) a locking nut and (c) a coaxial line extending through said locking nut and said tubular insert and terminating in an electromagnetic energy probe,

(1) said tubular insert being dimensioned to freely receive said coaxial line and having end portions provided with axially extending slots through the walls thereof and a solid central mounting portion separating said end portions, one of said end portions having an external threaded section and an external tapered section, said other slotted end portion having multiple parallel cantilevers containing said coaxial line,

(2) said locking nut having an internal threaded section and an internal tapered section and being dimensioned to freely slide over said coaxial line, said internal threaded portion of said nut engaging said external threaded section of said insert and said internal tapered section of said nut engaging said external tapered section of said insert whereby when said nut is tightened onto said tubular insert by engagement of said threaded sections, said slotted external tapered section of said tubular insert is circumferentially clamped against said coaxial line by engagement of said tapered sections.

References Cited UNITED STATES PATENTS portion provided with axially extending slots 2483337 9/1949 Dolberg 33382 through the wall thereof and a solid mounting 256L'417 7/1951 Ryan et 333 82 portion for engaging said aperture in said wall. 2561727 7/1951 et 33382 8, A coupling apparatus for use with an electromag 3155930 11/1964 Loveloy 333 97 n tic energy containing structure having an apertured wall 3160825 12/1964 Den 333*83 said coupling apparatus comprising: 3,209,289 9/1965 Golden et al 33383 (a) a tubular insert and (b) a coaxial line extending through said tubular insert and terminating in an electromagnetic probe,

(1) said tubular insert being dimensioned to freely HEJRMAN KARL SAALBACH, Primary Examiner,

L LLAH A si tant Ex m e UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,324,425 June 6, 1967 Richard H. Swartley It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 34, aperture" should read apertured Column 5, line 24, "sloted" should read slotted Column 6, line 23, "containing" should read contacting Signed and sealed this 30th day of December 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents 

7. AN ADJUSTABLE COUPLING APPARATUS FOR USE WITH AN ELECTROMAGNETIC ENERGY CONTAINING STRUCTURE HAVING AN APERTURED WALL AND ADJUSTABLE COUPLING APPARATUS, SAID WALL HOUSING IN SPACED RELATION AN INNER ELECTRICAL CONDUCTOR, SAID ADJUSTABLE COUPLING APPARATUS COMPRISING: (A) A TUBULAR INSERT AND (B) A COAXIAL LINE EXTENDING THROUGH SAID TUBULAR INSERT AND TERMINATING IN AN ELECTROMAGNETIC PROBE LOCATED ADJACENT SAID INNER ELECTRICAL CONDUCTOR AND IN SPACED RELATION WITH SAID WALL AND SAID INNER CONDUCTOR, (1) SAID TUBULAR INSERT BEING DIMENSIONED TO FREELY RECEIVE SAID COAXIAL LINE AND HAVING AN END PORTION PROVIDED WITH AXIALLY EXTENDING SLOTS THROUGH THE WALL THEREOF AND A SOLID MOUNTING PORTION FOR ENGAGING SAID APERTURE IN SAID WALL. 